/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/*
 *  Generic ASN.1 parsing
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#include "tls/config.h"

#if defined(MBEDTLS_ASN1_PARSE_C)

#include "tls/asn1.h"

#include <string.h>

#if defined(MBEDTLS_BIGNUM_C)
#include "tls/bignum.h"
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc    calloc
#define mbedtls_free       free
#endif

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
	volatile unsigned char *p = (unsigned char *)v;
	while (n--) {
		*p++ = 0;
	}
}

/*
 * ASN.1 DER decoding routines
 */
int mbedtls_asn1_get_len(unsigned char **p, const unsigned char *end, size_t *len)
{
	if ((end - *p) < 1) {
		return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
	}

	if ((**p & 0x80) == 0) {
		*len = *(*p)++;
	} else {
		switch (**p & 0x7F) {
		case 1:
			if ((end - *p) < 2) {
				return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
			}

			*len = (*p)[1];
			(*p) += 2;
			break;

		case 2:
			if ((end - *p) < 3) {
				return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
			}

			*len = ((size_t)(*p)[1] << 8) | (*p)[2];
			(*p) += 3;
			break;

		case 3:
			if ((end - *p) < 4) {
				return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
			}

			*len = ((size_t)(*p)[1] << 16) | ((size_t)(*p)[2] << 8) | (*p)[3];
			(*p) += 4;
			break;

		case 4:
			if ((end - *p) < 5) {
				return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
			}

			*len = ((size_t)(*p)[1] << 24) | ((size_t)(*p)[2] << 16) | ((size_t)(*p)[3] << 8) | (*p)[4];
			(*p) += 5;
			break;

		default:
			return (MBEDTLS_ERR_ASN1_INVALID_LENGTH);
		}
	}

	if (*len > (size_t)(end - *p)) {
		return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
	}

	return (0);
}

int mbedtls_asn1_get_tag(unsigned char **p, const unsigned char *end, size_t *len, int tag)
{
	if ((end - *p) < 1) {
		return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
	}

	if (**p != tag) {
		return (MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
	}

	(*p)++;

	return (mbedtls_asn1_get_len(p, end, len));
}

int mbedtls_asn1_get_bool(unsigned char **p, const unsigned char *end, int *val)
{
	int ret;
	size_t len;

	if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_BOOLEAN)) != 0) {
		return (ret);
	}

	if (len != 1) {
		return (MBEDTLS_ERR_ASN1_INVALID_LENGTH);
	}

	*val = (**p != 0) ? 1 : 0;
	(*p)++;

	return (0);
}

int mbedtls_asn1_get_int(unsigned char **p, const unsigned char *end, int *val)
{
	int ret;
	size_t len;

	if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_INTEGER)) != 0) {
		return (ret);
	}

	if (len == 0 || len > sizeof(int) || (**p & 0x80) != 0) {
		return (MBEDTLS_ERR_ASN1_INVALID_LENGTH);
	}

	*val = 0;

	while (len-- > 0) {
		*val = (*val << 8) | **p;
		(*p)++;
	}

	return (0);
}

#if defined(MBEDTLS_BIGNUM_C)
int mbedtls_asn1_get_mpi(unsigned char **p, const unsigned char *end, mbedtls_mpi *X)
{
	int ret;
	size_t len;

	if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_INTEGER)) != 0) {
		return (ret);
	}

	ret = mbedtls_mpi_read_binary(X, *p, len);

	*p += len;

	return (ret);
}
#endif							/* MBEDTLS_BIGNUM_C */

int mbedtls_asn1_get_bitstring(unsigned char **p, const unsigned char *end, mbedtls_asn1_bitstring *bs)
{
	int ret;

	/* Certificate type is a single byte bitstring */
	if ((ret = mbedtls_asn1_get_tag(p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING)) != 0) {
		return (ret);
	}

	/* Check length, subtract one for actual bit string length */
	if (bs->len < 1) {
		return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
	}
	bs->len -= 1;

	/* Get number of unused bits, ensure unused bits <= 7 */
	bs->unused_bits = **p;
	if (bs->unused_bits > 7) {
		return (MBEDTLS_ERR_ASN1_INVALID_LENGTH);
	}
	(*p)++;

	/* Get actual bitstring */
	bs->p = *p;
	*p += bs->len;

	if (*p != end) {
		return (MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
	}

	return (0);
}

/*
 * Get a bit string without unused bits
 */
int mbedtls_asn1_get_bitstring_null(unsigned char **p, const unsigned char *end, size_t *len)
{
	int ret;

	if ((ret = mbedtls_asn1_get_tag(p, end, len, MBEDTLS_ASN1_BIT_STRING)) != 0) {
		return (ret);
	}

	if ((*len)-- < 2 || *(*p)++ != 0) {
		return (MBEDTLS_ERR_ASN1_INVALID_DATA);
	}

	return (0);
}

/*
 *  Parses and splits an ASN.1 "SEQUENCE OF <tag>"
 */
int mbedtls_asn1_get_sequence_of(unsigned char **p, const unsigned char *end, mbedtls_asn1_sequence *cur, int tag)
{
	int ret;
	size_t len;
	mbedtls_asn1_buf *buf;

	/* Get main sequence tag */
	if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
		return (ret);
	}

	if (*p + len != end) {
		return (MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
	}

	while (*p < end) {
		buf = &(cur->buf);
		buf->tag = **p;

		if ((ret = mbedtls_asn1_get_tag(p, end, &buf->len, tag)) != 0) {
			return (ret);
		}

		buf->p = *p;
		*p += buf->len;

		/* Allocate and assign next pointer */
		if (*p < end) {
			cur->next = (mbedtls_asn1_sequence *) mbedtls_calloc(1, sizeof(mbedtls_asn1_sequence));

			if (cur->next == NULL) {
				return (MBEDTLS_ERR_ASN1_ALLOC_FAILED);
			}

			cur = cur->next;
		}
	}

	/* Set final sequence entry's next pointer to NULL */
	cur->next = NULL;

	if (*p != end) {
		return (MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
	}

	return (0);
}

int mbedtls_asn1_get_alg(unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params)
{
	int ret;
	size_t len;

	if ((ret = mbedtls_asn1_get_tag(p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
		return (ret);
	}

	if ((end - *p) < 1) {
		return (MBEDTLS_ERR_ASN1_OUT_OF_DATA);
	}

	alg->tag = **p;
	end = *p + len;

	if ((ret = mbedtls_asn1_get_tag(p, end, &alg->len, MBEDTLS_ASN1_OID)) != 0) {
		return (ret);
	}

	alg->p = *p;
	*p += alg->len;

	if (*p == end) {
		mbedtls_zeroize(params, sizeof(mbedtls_asn1_buf));
		return (0);
	}

	params->tag = **p;
	(*p)++;

	if ((ret = mbedtls_asn1_get_len(p, end, &params->len)) != 0) {
		return (ret);
	}

	params->p = *p;
	*p += params->len;

	if (*p != end) {
		return (MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
	}

	return (0);
}

int mbedtls_asn1_get_alg_null(unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg)
{
	int ret;
	mbedtls_asn1_buf params;

	memset(&params, 0, sizeof(mbedtls_asn1_buf));

	if ((ret = mbedtls_asn1_get_alg(p, end, alg, &params)) != 0) {
		return (ret);
	}

	if ((params.tag != MBEDTLS_ASN1_NULL && params.tag != 0) || params.len != 0) {
		return (MBEDTLS_ERR_ASN1_INVALID_DATA);
	}

	return (0);
}

void mbedtls_asn1_free_named_data(mbedtls_asn1_named_data *cur)
{
	if (cur == NULL) {
		return;
	}

	mbedtls_free(cur->oid.p);
	mbedtls_free(cur->val.p);

	mbedtls_zeroize(cur, sizeof(mbedtls_asn1_named_data));
}

void mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data **head)
{
	mbedtls_asn1_named_data *cur;

	while ((cur = *head) != NULL) {
		*head = cur->next;
		mbedtls_asn1_free_named_data(cur);
		mbedtls_free(cur);
	}
}

mbedtls_asn1_named_data *mbedtls_asn1_find_named_data(mbedtls_asn1_named_data *list, const char *oid, size_t len)
{
	while (list != NULL) {
		if (list->oid.len == len && memcmp(list->oid.p, oid, len) == 0) {
			break;
		}

		list = list->next;
	}

	return (list);
}

#endif							/* MBEDTLS_ASN1_PARSE_C */
